It is conventional practice to employ flat or conical washers beneath the head of a threaded fastener, such as a screw or nut, to help distribute the clamping stresses and load against the underlying structure. Such washers typically have relatively sharp edges that can abrade and damage the underlying structure such as a solar panel, particularly when the underlying structure is subjected to vibrations such as wind forces against a solar panel. It is a general object of the present disclosure to provide a fastener arrangement that addresses these shortcomings in the prior art.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A fastener arrangement in accordance with one aspect of the present disclosure includes a threaded fastener, such as a screw or nut, having a head with an undersurface. A washer is disposed adjacent to the undersurface of the fastener head. The washer has a domed central portion that is outwardly convex beneath the head undersurface, a center opening, and a curled periphery that is outwardly concave adjacent to a periphery of the fastener head undersurface. When the fastener is threadably tightened against the washer, the fastener head collapses the central portion of the washer against the underlying structure and curls the periphery of the washer around the periphery of the head. The washer preferably comprises a body of revolution around the axis of its center opening. The fastener preferably comprises a screw with a threaded shank that extends through the center opening of the washer and to which the washer is assembled.
According to another aspect of the disclosure, a washer includes a domed central portion with a central opening establishing a longitudinal axis, a base wall extending in a direction radially outwardly from the axis, and an extension wall extending in a direction radially outwardly and axially away from the base wall. The washer also includes a curled radially outer periphery with a peripheral wall extending radially outwardly from the extension wall and in a direction axially away from the extension wall back toward the base wall. A fastener assembly includes the washer and a fastener having a shank extending through the central opening of the central portion. A fastener arrangement includes the fastener assembly and an object to which the fastener assembly is fastened. A product includes the fastener arrangement and a panel carried by an underlying structure to which the shank of the fastener assembly is coupled, with the curled radially outer periphery engaging the panel.
According to a further aspect of the disclosure, a method of producing a fastened product includes the following steps. A fastener assembly is coupled to an object, wherein the fastener assembly includes a fastener with a head and a shank extending from the head and coupled to an underlying structure, and a washer having a domed central portion with a central opening establishing a longitudinal axis and through which the fastener shank extends, a base wall extending in a direction radially outwardly from the axis, and an extension wall extending in a direction radially outwardly and axially away from the base wall, the washer also having a curled radially outer periphery with a peripheral wall extending in a direction radially outwardly and axially away from the extension wall back toward the base wall, wherein a rounded portion of the curled radially outer periphery engages a panel of the object that is carried by the underlying structure. Also, the fastener assembly is tightened to the underlying structure such that the central portion at least partially collapses and a radially outermost edge of the washer turns away from the panel. A product is produced by the method.